The invention relates to a process for producing light weight concrete including a binding agent, e.g. cement, an inorganic aggregate, e.g. sand, and foamed plastic material, e,g. foamed polystyrene, whereby the granulated plastic material is supplied into the mixer by a metering mechanism.
Furthermore the invention relates to a device for the realisation of this process and comprising a mixer and supply means for the granulated plastic material.
In the production of light weight concrete with admixtures of foamed plastic material, e.g. foamed polystyrene, it has proven to be an advantage to foam up the plastic material directly in the concrete mixer itself.
The foaming up of the plastic material is carried out under a certain pressure, which, in the case of polystyrene, ranges between 0.0 and 0.5 atm gage, and at a certain temperature which is 100.degree. - 110.degree. C according to prior art.
The supply of the granulated plastic material causes difficulties due to the pressure conditions in the mixer. According to prior art it is practically necessary to reduce the pressure in the mixer before the granulated material is added, i.e. before every mixing turn, a fact that causes considerable losses in time and energy.
Another reason for which it is impossible according to prior art to introduce the granulated plastic material into the mixer, which is under a certain pressure, is constituted by the fact that congestions and agglomeration of lumping can occur at the inlet into the mixer. The consequences of this disadvantage are difficulties in production and weak zones in the concrete due to the agglomeration.